Cross sectional Transmission Electron Microscope (TEM) image of the top half of an amorphous silicon (a-Si:H) solar cell with a very high open circuit voltage. The nanocrystals can be seen clearly in the p-layer. The scale in nanometers (nm) is shown at the bottom left. This image was taken at the National Renewable Energy Laboratory compliments of Mowafak Al-Jassim and Kim Jones.

Abstract:
The Clarion University Nanotechnology program just contributed in a "small" way to the goal of helping stave off the effects of climate destabilization.

Clarion nanotechnology helps improve solar cell performance

Clarion, PA | Posted on June 7th, 2007

The latest news from the Intergovernmental Panel on Climate Change is that stark - climate destabilization is underway, its potential effects are catastrophic, and something must be done about climate change before it gets completely beyond control. One way society can reduce the threat is evolve to the use of renewable energy sources such as solar.

The project was completed in collaboration with Dr. Nik Podraza and Dr. Robert Collins at the University of Toledo, Dr. Mowafak Al-Jassim and Kim Jones at the National Renewable Energy Laboratory, and Dr. Jingdong Deng and Dr. Christopher Wronski at Penn State University.

Although, technically efficient enough solar cells are already on the market and actually often sold out because demand continues to outstrip supply, further development in solar energy is needed for society to meet its enormous projected energy demands without emitting greenhouse gases from burning conventional fossil fuels. Less than one percent of the global energy demand is provided by solar cells.

"This research project focused on increasing the open circuit voltage (VOC), one determinant of the amount of power a solar cell can produce, in "second generation" thin film amorphous silicon solar cells in order to improve their efficiency," said Pearce.

The origins of the high open circuit voltages in amorphous silicon solar cells having p-layers prepared with very high hydrogen dilution and the physical structure of these optimum p-layers were both poorly understood topics, with several studies offering conflicting views.

"Our paper overcame limitations of previous studies by combining insights available from electronic measurements, real time spectroscopic ellipsometry, and the latest armada of nanotechnology characterization tools: atomic force microscopy, high-resolution transmission electron microscopy (TEM) and dark field TEM of cross-sections of entire solar cells," said Pearce. "We found that solar cells fabricated with p-layers having a low density of nanocrystals imbedded in a protocrystalline silicon matrix had lower losses than standard cells and would deliver a higher VOC. Practically, this means that solar cells having this density of nanocrystals were not harmed and could obtain higher efficiencies if all other factors remained the same.

"I have little doubt that solar is the way of the future. Most people are ‘pro-solar' - they know the dangers of our current energy habits and we are slowly moving in the right direction. The problem is our evolution is slow - the future may arrive before we are ready. We need young people to start considering work in renewable energy and complimentary fields like nanotechnology. We need many more scientists and engineers to start working on and solving our energy problems. We need citizens to start taking the repercussions of their energy choices seriously and we need new leaders to provide a vision of hope for our children."

Nanotechnology is any technology related to features of nanometer scale, one billionth of a meter: thin films, fine particles, chemical synthesis, advanced micro-lithography, and atomic/molecular engineering. Nanotechnology is igniting a scientific revolution as scientists begin to manipulate atoms and molecules as if they were tiny Lego blocks.

Amorphous silicon solar cells, like those in this study, will be integrated into the roof of Clarion University's Science and Technology Center (currently under construction) to provide solar electricity to power the building.

For additional information about Clarion University's Nanotechnology Program see or for information on solar energy contact Dr. Pearce at 814-393-2713 or at .